The invention relates to the production of aluminium materials, and in particular to the production of damage tolerant wrought aluminium materials.
From the prior art it is known that for conventionally produced aluminium materials, strength, ductility and damage tolerance are generally inversely related to one another such that an increased level of tensile strength usually deteriorate ductility and damage tolerance
In a previous method known from EP1987170 an alloy is used comprising wt %: Mn max 0.6, Cr max 0.3, Zr max 0.25, Mg 0.25-1.2, Si 0.3-1.4, Ti 0.1-0.4, where Ti is present in solid solution and incidental impurities, including Fe and Zn, up to 0.5 is included, with the balance being Al. The preferred Si/Mg-ratio is 1.4. The alloy is cast to billets and then homogenised and the billets are extruded to produce a material with improved crush resistant properties.
Extruded or rolled material resistant to stress corrosion cracking is presented in JP2008076297. The compositions used in this patent result in a conventional microstructure with a homogenous distribution of alloying elements. This patent also claims that the casting rate and cooling rate after casting must be high to keep the grain size of the cast structure small. A material of high damage tolerance is hereby not produced.
In EP2103701 an aluminium alloy comprising Si 0.68-0.77, Fe 0.16-0.24, Cu 0.24-0.32, Mn 0.68-0.77, Mg 0.58-0.67, Cr<0.04, Zn<0.1, Ti<0.1, V<0.04, other elements <0.3, balance Al is used to produce products for the automotive industry with a yield strength of more than 280 MPa.